This invention relates to laser systems capable of multiple pulse operation.
There is a need for a laser system which can produce multiple pulses having a controllable separation between pulses. For instance, such a system is useful in systems performing averaged cross-wind velocity measurements by using a correlation technique, and in incoherent designator systems.
One technique that may be used is to employ two separate lasers pulsing consecutively. The multiple pulses are then transmitted along the same optical axis. The problem is that the mode from the different lasers are not exactly the same, thus causing problems in applications requiring correlation between the pulses. Additionally, it is extremely difficult to maintain the required alignment stability between the two lasers. Another technique which may be used consists of pulsing a standard laser at the required interval to produce the multiple pulses. A problem with this is that it requires a power supply with a high enough current capability to recharge the energy storage capacitors in less than the minimum interval required. Another problem is that when the laser is pulsed with a short interval between pulses, as required in certain applications, the shock waves and the medium inhomogeneities produced by a first discharge do not substantially dissipate, prior to subsequent discharge, thus creating problems by interfering with the subsequent discharge.